The latest blog posts to take off on Hacker News. 2,393 posts.
Almost exactly a year ago, Google made one of the most remarkable press releases in the Web 2.0 era. Of course, by "press release", I actually mean keynote at their own conference, and by "remarkable" I mean potentially-transformative and groundbreaking. I am referring of course to the announcement of Google Wave , a…
I've been thinking about something that we always did junior year when I was on my high school soccer team. When we'd score a goal, we reali...
(You probably already have realized this.) The reason the compiler produced code that terminated was based upon the fact that the values being altered (i.e., a, b and c) within the “while” loop are never referenced again after the loop. But, once you added code which printed the resulting values it was forced to…
Currently, Apple's stock is at an all time high. A share today is worth over 40 times its value seven years ago. So, how much would you have today if you purchased stock instead of an Apple product? See for yourself in the table below. A huge thanks to everymac.com for the original prices and release dates. All values…
There are some programming books that I’ve read from cover to cover repeatedly; there are others that I have dipped into many times, reading a chapter or so at a time. Jon Bentley’s 19…
If a man can expect to meet exactly N eligible women in his life, what strategy should he use to maximize his chances of choosing the very best one? We typically make some idealized assumptions when solving this type of problem, such as assuming that he meets the women in random order of "goodness", that there is an…
All my life I've done mental arithmetic the 'wrong way': I've calculated from left-to-right, instead of right-to-left. So when I do somethi...
Ron Jeffries attempts to create a sudoku solver - here , here , here , here and here . (You really ought to read these articles. They are u...
Why everyday CRUD work needs little math, but search, machine learning, cryptography and other interesting fields need plenty.
The first two articles in this series, “ Regular Expression Matching Can Be Simple And Fast ” and “ Regular Expression Matching: the Virtual Machine Approach ,” introduced the foundation of DFA-based and NFA-based regular expression matching. Both were based on toy implementations optimized for teaching the basic…
I was really into fractals in college (I know…) when I was making rave flyers (I know!) for a friend’s parties in Iowa (I know! I know! Shut up already!). Anywa
Somehow I became the canonical undergraduate source for bibliographical references, so I thought I would leave a list behind before I graduated. I list the books I have found useful in my wanderings through mathematics (in a few cases, those I found especially un useful), and give short descriptions and comparisons…
The soft maximum approximates the maximum function, and approaches it in the limit, but is easier to work with.
I recently learned an interesting fact about Fibonacci numbers while watching a random number theory video on YouTube. Fibonacci numbers can be used to approximately convert from miles to kilometers and back. Here is how. Take two consecutive Fibonacci numbers, for example 5 and 8. And you're done converting. No...
In preparation for my upcoming course on random matrices, I am briefly reviewing some relevant foundational aspects of probability theory, as well as setting up basic probabilistic notation that we…
A/B testing tools often lie about whether something is "statistically significant." Here's an extremely simple, mathematically sound formula to compute it for yourself.
From the highly eclectic blog of Mark Dominus
Name the most widely used bytecode interpreter or virtual machine. Sun's JVM? Adobe's Flash? .NET and Mono? Perl? Python? PHP? These are all certainly popular, but there's one more widely used than all those combined. That bytecode interpreter is Henry Spencer's regular expression library and its many descendants.
Click on the picture for bigger view. Roots of quadratic polynomials are in grey; roots of cubics are in cyan; roots of quartics are in red and roots of quintics are in black. The horizontal axis of symmetry is the real axis; the vertical axis of symmetry is the imaginary axis. The big hole in the middle is centered…
The 17x17 challenge: worth $289.00. I am not kidding. Definition: The n x m grid is c-colorable if there is a way to c-color the vertic...
As you all may know, I watched and posted my lecture notes of the whole MIT Introduction to Algorithms course. In this post I want to summarize all the topics that were covered in the lectures and point out some of the most interesting things in them. Actually, before I wrote this article, I had started writing an...
I’ve programmed in many languages before, indeed I’ve spent at least a year working in Basic, C, C++, C#, java, assembler, modula-2, powerhouse and prolog. One thing I’ve never done before is Matlab, well except a few basic exercises for some course I did way back. A couple of years ago I started using python and more…
Visa,Master Card,Discover, and American Express credit card validation and generation techniques using the luhn algorithm.
Reading how shocked Doron Zeilberger is at the state of modern mathematics reminded me of why I left the subject. Math departments regularl...
I just came back from attending the 1052nd AMS (sectional) meeting at Penn State, last weekend, and realized that the Kingdom of Mathematics is dead. Instead we have a disjoint union of narrow specialties , and people who know everything about nothing, and nothing about anything (except their very narrow acre). Not…
Busy Beaver puts another one on the Turing Machine's tape (image from the book The New Turing Omnibus). The busy beaver problem is a fun theoretical computer science problem. Intuitively, the problem is to find the smallest program that outputs as many data as possible and eventually halts. More formally it goes…
Peter Henderson wrote an article about a method to describe pictures with functional programs. I've implemented it in Lisp. An updated version of the article uses curves and different shapes and has some references to other applications for this method, like "An Algebra of Music".
